Deterioration of vision is a common problem in the elderly and in recent studies has been demonstrated to be an independent and important contributor to physical disability and frailty. Age associated loss of vision can result from aging and from age-associated pathology. The natural history of vision loss has not been well studied in relationship to the development of eye and other pathology and the differentiation between normal visual aging and pathological changes in vision. Furthermore, little attention has been given to what factors may prevent aging changes in vision and what environmental factors can be altered as the changes begin to occur and as they progress. Research in the BLSA has been designed to address aspects of these age associated changes. (1) Natural history studies have been done for many years, and several longitudinal studies have been reported. A laboratory based assessment of visual contrast sensitivity continues to be administered, increasing the number of persons with at least two measures to over two hundred. (2) A new study of the relationship between intraocular pressure and systemic blood pressure was begun in July 1994. The study will identify possible racial and sex differences in blood pressure/intraocular pressure relationships and the effect of the relationship on vision as measured by changes in the visual field.